/*要求：找出字符串中第一个不重复的字符。
输入样例：
google
输出样例：
l
*/
#include<stdio.h>
#include<string.h>
#define SIZE 1001
char firstNOnRepeatingChar(char *str)
{
    if (str == NULL || strlen(str) == 0)
    {
        return '\0';
    }
    
    int charCount[256] = {0};
    for (int i = 0; str[i] != '\0'; i++)
    {
        charCount[(unsigned char)str[i]]++;
    }
    
    for (int i = 0; str[i] != '\0'; i++)
    {
        if (charCount[(unsigned char)str[i]] == 1)
        {
            return str[i];
        }
        
    }
    
    return '\0';
}

int main()
{
    char repeat ;
    char words[SIZE];
    fgets(words, SIZE, stdin);
    repeat = firstNOnRepeatingChar(words);
    printf("%c", repeat);
    return 0;
}